Refrigeration apparatus



Feb. 18; 1936.-

T. s. sAFFoRD 2,030,942

REFRIGERATION APPARATUS Filed May 20, 1932 5 Sheets-Sheet 1 iNvEN'roRRUM/4N 5. SAFfo/m Feb. 18, 1936.

T. s, SAI-'FORDv REFRIGERATION APPARATUS Filed May 20, 1952 5Shee'os-Sheefl 2 T. s. SAFFORD REFRIGERATION APPARATUS Feb. 1 8, 1936.

Filed May 20, 1952 5 Sheets-Sheet E INVENTOR l TR1/MAN S. SA Fra/w Feb.18, 1936. T. s. sAFFoRD 2,030,942

REFRIGERATION APPARATUS I Filed May 20, 1952 5 Sheets-Sheet 4 9 TLF-fj?95 95 INVENTOR TRL/MAN' S SAfFoRo Feb. 1s, 1936. T s SAFFORD 2,030,942 fREFRIGERATI ON APPARATU Filed May 20, 1952 5 Sheecs--Sheecl 5 Kati theother leg of the Patented Feb. 18, 1936 UNITED STATES PATENT GFFICE 18Claims.

This invention rel-ates to a refrigerating apparatus and method and to amethod and apparatus for compressing and/ or circulating a fluid. Moreparticularly, the invention relates to an apparatus in which compressionand/or circulation of a fluid, e. g., a. refrigerating fluid, is eiectedby means of-a moving body of liquid impelled dieciy by vaporization andcondensation of a Prior to my invention, various devices have beensuggested in which alternate vaporization and condensation were to beutilized to create a reciprocating pressure on the surface of a columnof liquid which was to be moved thereby to effect the desiredcompression or circulation. Thus, for example, in one suggestedconstruction, water was to be boiled or decomposed in one leg of aU-tube to drive the remainder ofthe water into tube, there to compress arefrigerant vapor, but with this suggested construction, it has beenfound that the water vapor passes over into the refrigerant cycle andthe refrigerant dissolves inthe water and is carried over into thevaporizing side of the tube, whereV it is boiled out and collectsuncondensed until very soon the entire apparatus is renderedinoperative. No construction has been known which could be operativeover any substantial period to compress a vapor, e. g., asA required ina refrigerator cycle, or which could be economically practicable incompetition with other methods of compression and refrigeration. y

I have now discovered that it is possible to overcome thesedifliculties, and acc'ordingly I have provided a simple device whichwill operate satisfactorily for any length of time and at costs whichcompare favorably with those of other compressing and refrigeratingmeans.

There are obvious advantages of simplicity and entire freedom fromleakage and wear which make this type of compressor system verydesirable where the over-balancing defects are eliminated.

It is, therefore, an object of the present invention to provide acompressor of this type in which the gas or vapor which is compressedtherein is prevented from collecting in the apparatus. It is also anobject of the invention to so design such an apparatus as to eliminatewaste of heat and to reduce its operating costs so as favorably tocompare with those of other compressing means.- A further object of theinvention is to provide a refrigerating apparatus in which the fluid ofthe compressor is prevented from collecting in the refrigerating side ofthe apparatus,

and the refrigerant is prevented from collecting in the compressor sideof the apparatus.

Another object of the invention is to provide a refrigerating apparatus,especially for domestic refrigerators which will operate without noise 5or vibration and Without Wear, which will be hermetically sealed toprevent any possibility of leakage and which will operate indefinitelywithout service diiculties.

A Apparatus designed according to the present 10 invention to achievethese and other objects is shown in the accompanying drawings, in which:

Fig. 1 is a diagrammatic View, partly in vertical section, of arefrigeration apparatus designedv especially for domestic refrigeration;15 Y Fig. 2 is a diagrammatic view similar to- Fig. 1, but simplifiedtherefrom to show the relation oi liquid levels in the various parts ofthe apparatus;

Figs. 3 and 4 are diagrammatic views similar to Fig. 2, but showingdifferent stages of the 20 cycle; 4

Fig. 5 is a view, partly in vertical section, of another form ofrefrigerating apparatus embodying the invention; s

Fig. 6 is a view in vertical section of another 25 formof refrigeratingapparatus desirable for use in the apparatus of the present invention;

Fig. '7 is a horizontal section taken on line 'I-l of Fig. 6;

Fig. 8 is a view similar to Fig. 1 of a modified 30 form of theinvention; y

Figs. 9 and 10 are detail views of a portion of the apparatus of Fig. 1showing alternative methods of venting gases from 'the compressor backlto the refrigeration side of the cycle;

Fig. 11 is a view partly in horizontal section, as indicated by lineIl-H on Fig. 12, of a two stage interrelated apparatus similar to thatshown in Fig. 8; and

Fig. 12 is a vertical section taken on line |2-I2 40 of Fig. 11.

Fig. 13 is a wiring diagram illustrating a method of heat control whichmay be used as an alternative to that described in connection with otherfigures.

vReferring rst to Fig. 1, I have shown at the right hand side of thisgure a refrigerating apparatus similar to the compression type commonlyused. 'I'his consistsof a. compressor chamber 20, a condenser 2|, and anevaporator-refrigerator 50 22, with a connection between the evaporatorand the compression chamber controlled lby a check-valve 23, aconnection between the condenser and the compression chamber controlledby a check valve 24. and a connection between ts A liquid in thecompression chamber 20 serves as a piston alternately to draw inrefrigerant vapor at low pressure and to expel it at high pressure. Thebottom of the compression chamber 20 is connected to the expansionchamber 30 by a passage 26, and also to tht` condenser 3| by a passage21. The liquid level is at all times above these connections and thevolume of the liquid is such that when the compression chamber con- Atains a full charge of refrigerant vapor at low pressure, as shown, e.g., in Fig. 2, the condenser -3| and the expansion chamber 30 -are fullof liquid, asare also the U-tube connection 32 between the top of theexpansion chamber and the top of the condenser, the measuring chamber 33and both of the connections 26 and 21.

A passage 34 connects the top of the expansion chamber 30, the top ofthe passage 32 and the top of the measuring chamber 33, and alsoconnects these with a boiler chamber 35, which in the present case isheated by a. surface 4combustion heater 36 supplied with a combustiblegas mixture by the tube 31. l

This boiler 35 is preferably designed to store up a relatively largeamount of heat and to superheat the vapors formed therein. To this end,a

number of baiiles are shown in the drawings, but it is to be understoodthat any other means may be adopted for this', purpose, e. g., theboiler may be filled with loose bailling material of high heat capacityand heat conductivity, such as turnings or irregularly shaped pieces ofaluminum orl copper.

A syphon 39 connects the bottom of the measuring chamber 33 to thebottom of the boiler at a level just below the bottom of connectingpascooling surfaces 42 and external fins or otherextended surfaces 43serve to transfer the heat rapidly from the vapor into the cooling airand to effect rapid condensation of the vapor.

A stack 45 serves to`carry oif the combustion gases fromthe boiler 35and the heated air from the condensers 3| and 2 and the draft from thisstack serves to maintain a rapid circulation over thecooling surfaces ofthe condensers. It will be understood also that the gases of thecombustiblegas mixture may be preheatedby heat-exchange from any ofthese three sources. The jackets 46 and 41 serve to direct the aircirculation close to the heat-exchange surfaces of the condensers.

As this apparatus just described stands idle, the vapors of the liquidare condensed in 3| so that the liquid level .rises to the top of thatchamber,

and therefore fills the U-passage 32, the measuring chamber 33, and theexpansion chamber 30,

and is drawn out fromthe compression chamber 20 causing the vapors ofthe refrigerant, evaporated in 22, to substantially fill said chamber20.

Upon heating of the boiler 35, the liquid, which has been syphoned overthrough 39 from the measuring chamber 33, is boiled and the vapors thusformed are superheated and passed over into the `:hamber 30, Where itforces displacement of the liquid therefrom. Since the condenser 3| isalready filled, there is only one escape for the disthe condenser andevaporator controlled by the. float valve 25.

placed liquid, that'is, into the compressionchamber 20.

The displacement of the. liquid from the expansion chamber 30 into thecompression chamber 20 results in the compression of the refrigerantvapor therein and eventually in their displacement from the compressionchamber through the valve 24 into the condenser 2|.

During the displacement of the liquid from the chamber 3|), the level inthe connecting tube 3'2 must, obviously, remain the same as that in thechamber 30. The charge of liquid in the measuring chamber 33 is slightlymore than enough to `depress the liquid to the level of the bottom ofthe U-connection 32, e. g., as shown in Fig. 3. At this point thecompression chamber is substantially lled with the liquid'and therefrigerant substantially entirely driven out. When this point has beenreached, however, no further displacement of the liquid can occur, andthere is no danger of the liquid being driven up through the valve 24into the refrigerating cycle.

The additional vapors produced by the boiling of the last of the liquidfrom the measuringV chamber 33, instead of displacing more liquid fromthe chamber 30, escapes through the co'n-v nection 32, and as it bubblesup on' the other side of the U, the liquid seal therein isbroken and an'inverted vapor-syphon is formed therein.-

Immediately the liquid in the chamber 30 and the condenser 3| tends toseek a common level,

as shown in' Fig. 4; and as condensation occurs in the condenser 3|, thelevels in the two remain substantially equal until the liquid has risenthereinsufficiently to spill over into the connection 32 and to restorethereby the liquid seal between 3|! and 3|.

When this stage is reached, the liquid has been drawn out from thecompression chamber 20 and has been replaced therein lby a fresh chargeof refrigerant vapor at low pressure, and thus is restored to thecondition illustrated by Fig. 2.

`At the same time that the liquid spills over into 32,it also fills themeasuring chamber 33, but it cannot ll the syphon 39 so asto start thefeed to the boiler until the connectionV 32 has been-filled, because thesyphon tube 39 `is substantially above the level of the top of the wallbetween the tube 32 and the measuring chamber 33.

As soon as the tube 32 has been filled so that the level can rise abovethe syphon 39, the feed to the boiler begins and the superheated vaporat once begins to drive down the level in the chamber 30 and the tube32. Thus the cycle is repeated indefinitely.

Although the device as just described can be operated with continuousheating of the boiler, and ordinarily would be so operated where aliquid fuelis used,`I have illustrated in Fig. 1 an apparatus adaptedfor intermittent operation, e. g., with gaseous fuel. Where continuousheating is used, the boiler is merely storing up heat by raising thetemperature of its walls and bailies, etc., and this heat issubsequently used for boiling. the liquid and superheating the resultingvapors. Where an easily controlled source of heat is used, it isordinarily more economical to use intermittent heating andv for thispurpose a thermostat is provided controllingA the valve 4| in the gasline 31 (or in the steam `line ora switch in an electrical heatingcircuit, or other heat control means).

When the liquid seal is broken at the end of the first step" of thecycle (as shown at Fig. 3),

frigerant which are chosen.

vagrancy of the materials and to conne them,

- ticular liquid chosen the materials chosen for very hot vapors passover through the connection 32 and impinge upon the thermostat 40. Thesudden rise in temperature from that of the liquid which has beencooling in the condenser during the preceding step to that of the vaporsheated to the boiling point of the liquid at the highest operatingpressure causes the operation of the thermostat 40 to shut off theheating of the boiler 35. When, at the end of the condensing step, thesehot vapors are again converted into liquid at the lowest operatingpressure, the temperature is such as to cause the thermostat 43 again toturn on the heat for the boiler 35.

In the preferred embodiment, the heating means 36 is a. surfacecombustion gas heater. It may, however, be any other desired means forsupplying heat, as for example merely a jacket for circulation of a hotfluid, or an electric resistance heater. The surface combustion heaterhas proven most advantageous, both because of its superior heat exchangepossibilities and its more complete combustion, and because of the easewith which an ignition catalyst, e. g., palladium black, may besupported thereon so that intermittent heating with gas may be carriedon without the use of a pilot light or spark ignition means.

It is desirable for the sake of economy to avoid heat losses so far aspossible, except where condensation is eifected. Thus I have encased ininsulation 49 the boiler 35 with its heater 36, the chambers 33 and 30,the connections 34, 26 and 32, and the'bottom of the condenser 3|. It isto be understood, however, that such insulation may be extended fartheror omitted partially or entirely.

In the operation of this apparatus, there is likely to be more or lessrefrigerant dissolved in the boiling or piston liquid and more or lessVapor of the liquid mixed with the refrigerant vapor, depending upon theliquid and the re- To control this each to its own part of theapparatus, I have found it desirable to use a liquid which oats upon theboiling liquid, which has very low vapor pressures at the temperaturesto which it is subjected, and which does not appreciably dissolve therefrigerant vapor under the conditions met with in the compressionchamber 20. 'I'he parwill depend, of course, upon boiling liquid and forrefrigerant. Usingcarbon tetrachloride as the boiling liquid and methylchloride as the refrigerant, I have found that glycerine masI serve asthe sealing liquid between.

It is sometimes preferable not to use such a sealing liquid, or it maynot be possible to find a liquid which is inert, insoluble and of lowlvapor pressure as required for a given refrigerant and boiling liquidwhich it may be desired to use. In such case-and, in fact, even wheresuch a sealing liquid is used-it is advantageous to provide some meansof returning the accumulations of fugitive materials. Various devicesfor this purpose are shown in Figs. to 10.

Considering rst the fugitive refrigerant which may be dissolved in theboiling liquid and boiled out in the boiler 35, eventually collecting inthe condenser 3|, I have shown in Fig. 8 a preferred device forreturning such refrigerant vapors.

In Fig. 8 the expansion chamber 30, the connections 32 and 34, thesyphon 39, the measuring chamber 33 and the boiler 35 with its heater 36may all be the same as in Fig. 1. The compression chamber 20 issubstantially the same except that in this case it is higher than thechamber 30. The two are connected as before by the conduit 26. In thiscase, however, the condenser chamber 3| is smaller and at a higher leveland it is connected to the lower part of the compression chamber 20 by aconduit 3| a which is preferably level and provided with sufficientcooling surface to fully condense all vapors of the boiling liquidbefore they reach the chamber 20; this may be tortuous instead ofstraight.

In the operation of this embodiment of the lnvention, the first orcompression step proceeds as has already been described in connectionwith Fig. 1. In this case, however, once the liquid seal is broken inthe connection 32, the apparatus becomes merely a closed cycle systemwith vapors at a level below liquid, which naturally seek to rise to thetop of the liquid. The vapors therefore pass up into 3| and through 3|aand any which, during this travel, have escaped condensation may thusbubble through the liquid in chamber 20. The c'ondensers 3| and 3|a arearranged and designed so that the only vapors which will remain as suchat the surface of the liquid in chamber 20 will be the refrigerant va-Apors. All vapors of the boiling liquid will be condensed before thatpoint is reached.

Figs. 9 and 10 show alternative methods of venting refrigerant vapors.Fig. 9 shows an apparatus which may be substantially identical with thatshown in Fig. l, except for the thermostat 3|b and the connection 3| a,and that the compression chamber 20 is above the level of the condenser3|. In this case, the hot gases which come over through the connection32 at the end of the compression step of the cycle close thethermostatic valve 3|b, and this valve remains closedV untilcondensation has progressed sufficiently to avoid any danger of thevapors of the boiling liquid escaping uncondensed into the refrigerantspace. When this point has been reached, the valve is opened and thevapors of course pass over through the connection 3|a, either with orwithout further cooling and condensation therein.

The device shown in Fig. 10, although shown at the same levels as inFig. 9, is substantially independent of the relative levels, because ofthe use of two additional valves 3| c and 3Id. Near the end of thecompression step, the pressure in the entire apparatus is high and anyuncondensed gases remaining in the condenser 3| are forced through thevalve 3|c into the connecting passage 3la. At a subsequent stage in thecycle, when the pressure in the chamber 20 is low, the gases thuscompressed in 3|a. expand through the check valve 3|d and bubble upthrough the liquid in the chamber 20 to rejoin the refrigerant vapors.

In Figs. 5 to 7, I have illustrated by way of example how any fugitiveliquid may be returned from the refrigerating side of the cycle to thecompressor. As shown in Fig. 5, the cooling unit 22 is advantageouslypositioned above the level of the compression chamber 20 and as shown inFig. 1, the condenser 2| is advantageously above the level of thecooling unit 22. Thus the compressed vapors from the compressor chamber20 rise first to the top of the condenser 2|, from a series of bafileplates with staggered openings between, and each designed to maintain ashall low pool of liquid thereon, so that heat transmitted through themetal from the side wall will effect evaporation of the liquid.

In Figs. 6 and '7 is shown another and somewhat more desirable form ofbailled cooling unit. In this case, the baffles are designed to avoidpockets, and when this is used, there need be absolutely no place forthe fugitive boiling liquid to collect. The liquid coming from thecondenser 2| ows into the top of this unit onto the first of the bafiies55, and thence down over successive baiiles to the outlet 56l and backto the compressor chamber 20. Each of the baiiles is tilted slightly sothat the liquid will ow slowly thereacross and is made with staggeredridges 51 which require 'the liquid to follow a tortuous path over thebaille. Thus the liquid is extended over the surface of the baflies andrapid evaporation and heat transfer' effected.

In Fig. 5 I have shown also an alternative compressor unit. In this casethe compressor chamber 2U and the expansionl chamber 30 and theconnection 26 are shown of different shape, but their functions are thesame. In this case, howeverAthe condensation of the vapors during theintake step is effected entirely in the condenser connection 3Ia, andthe boiling is eifected in the expansion chamber by Aan electricalresistance heater 36a. and no separate boiling chamber, measuringchamber or condenser chamber is provided.

The connection 3Ia is controlled as in Fig.' 10 by check valves at eachend. In this case, however, the valve 3|c is a specially designed pistonvalve, while the valve 3|d is designed to operate with a very slightpressure difference caused by a relatively small difference of levelbetween the liquid in chamber 20 and that in chamber 30. This valve 31dmay be omitted entirely, but its use permits the condenser 3la to be ofsmaller capacity, since condensation may go on during a followingcompression step and a low pressure may result in the condenser whichwill cause more rapid clearing of thevapors from the expansion chamber.

The valve 3 Ic is made with a cam face 60 on its upper metallic surfaceand an annular cam groove 6I lined with an insulating material such as aporcelain enamel or a phenol formaldehyde resin, etc. 'Ihe upper conicalcam surface. 60 is so designed that when acted upon by the springpressed brushes`63, it will be held against its seat until subjected toa pressure greater than that at which the refrigerant is forced outthrough the valve 24. The -spring 64 and the insulating cam surfaces 6|and the brush springs 66 are so designed and related that the valve willbe held opened until the pressure is reduce'd sufiiciently to assurethat the vapor is all or largely expelled from the expansion chamber 30.

The heater 36a is supported on a core 68 secured to or integral with thehead of the chamber 30, and the circuit of the heater is connectedthrough the brushes 63 and the contact portion 60 of the valve 3Ic. Thuswhen the valve 3Ic is opened, the heating circuit is broken; and whenthe valve is closed, the heating circuit is reestablished.

In the construction shown, the heating circuit is connected to the righthand brush 63 and, through a connection not shown to the right handconducting link 69. The cover 10, with its insulating sleeves 1I, spring66, brushes 63, conducting sleeves 12, and conducting links 69, may befirst assembled. The intermediate part 68 may then be assembled with theheater 36a and the valve 3|e and the rivet or screw connections of thelinks 69 may be secure'd through the part 68 to the resistance elementof the heater 36a. All may then be assembled. The part 68 may be ofinsulating material such as bakelite, etc., or it maybe, as shown, ofmetal with insulating washers around the connections from the links 69to the heater 36a.

A float 15 and a back valve 16 are provided on the stem of valve 24 forthe purpose hereinafter explained.

In the operation of the device shown in Fig. 5, the liquid, which shouldll the apparatus above the level of the valve 3Id is rst boiled by theelectrical heater 36a. until the refrigerant vapor has beensubstantially entirely expelled through the valve 24. At this time, theliquid level nears the top of the chamber 20 and begins tov submerge thefloat 15. 'Upon further boiling of the liquid in 30, the liquid raisesthis float and presently closes the valve 16, whereupon, no furtherescape being possible, the pressure rises rapidly -within the apparatusuntil it is sufficient to open the valve 3Ic. When this occurs, theinsulating band 6| is interposed between the brushes 63 and the heatingcircuit is broken.

The vapors now pass out from the chamber 30 by the valve 3Ic into thecondenser 3Ia until the condensation has so reduced the pressure in `thechamber 30 as to allow the valve 3Ic to be float 15 to drop once more tothe position shown.'

This same system of valves and compressor may 'also be used with othertypes of heat and whether the boiling is effected within the expansionchamber or in 'a separate boilingchamber, as in Fig. 1. In the lattercase, the charge measured by chamber 33 should be enough to assure thebuilding up of excess pressure after the refrigerant charge isdischarged from the compression chamber 20. In either case, the heat maybe controlled directly by the valve 3Ic or by a separate pressureresponsive control, or by a circuit through 63 and 60, etc., and whichmay be used -to control the heating by operation of valves, etc.

In Figs. 11 and 12, I have illustrated a twostage compressor. Anarrangement of this kind makes possible considerably greater economythan is possible with the single compressor. In this case, theinitial'compressi-on is effected in the l When the compression step iscompleted on the right hand side, the vapors pass over from theexpansion chamber 3BR into the vapor dome 3 IR. and a specialcondenser-boiler heat-exchange unit and thence back to the compressionchamber 20B. In the heat-exchange unit 80, the vapor of the liquid usedin the right-hand side is condensed and gives up its latent and sensibleheat to the liquid used on the left-hand side. In the preferred form ofthe invention, the liquid used on the right-hand side boils at a muchhigher temperature than that used on the left, so that even at the lowerpressure existing in 2DR, as compared with 20L, the liquid used on thelefthand side will be boiled by heat transferred from the condensingvapors from the left-hand side. Thus, for example, I may use on theleft-hand side a substance such as butane or iso-butane, which boils atrelatively low temperatures at the highest pressures encountered, andfor the liquid used in the right-hand unit a substance which boils atrelatively high temperature even at the lowest pressure encountered.'I'he latent heat of vaporization and the specic heat in the boilingrange should, of course, be low if maximum economy is to be attained.Carbon-tetrachloride, trichlorethylene, hexane, heptane, and ethylalcohol are examples of liquids suitable for the right-hand side andbutane, iso-butane are examples of materialssuitable for the left-handside. The liquid used on the left side should preferably be one which atabout F. has a vapor pressure approximately the same as that at whichthe refrigerant is discharged from the first stage compressor 20L, andthis pressure is preferably chosen so that the heat of condensation fromthe first stage will be alittle more than enough to boil the entirecharge in the second stage.

The Waste gases 4from the boiler 3BR pass through the heat-exchanger 8|where, during the compression step on the left side, they serve tosuperheat the vapors generated in 80. During the remainder of the cycle,said gases store up heat in this heat-exchanger ready for the nextcompression step. From this heat-exchanger, the waste gases go to theflue 45.

When the operation of this two-stage device begins, the liquid in thecondenser and expansion chamber is cool, and therefore at a very lowvapor pressure; the compression chamber 2DR, therefore, i's full ofrefrigerant vapor. As the liquid is boiled in the boiler 3ER, the liquidlevel is driven down in the expansion chamber 3BR. and up in thecompression chamber ZUR.

The refrigerant in 20B, is rst compressed and then expelled through theconnection 82 and into the compression chamber 20L, ywhere it drivesdown the liquid level, increases the pressure on the vapors in thecondenser 3|L and causes condensation of the vapors in the condenseruntil the measuring chamber 33L is lled and the syphon 39L begins tofeed into the boiler-condenser 80.

In the meantime, the vapor from the expansion chamber 3DR, has brokenthe liquid seal in 32R and passed over into the vapor dome 3IR andtheboiler-condenser 80. In the latter, the vapor from 3DR. gives upits heatto the'liquid from 30L and is condensed while the latter is boiled.

The vapors boiledin80 and superheated in 8l return to the expansion'chamber 30L, where they drive. the liquid out into-thecompressionchamber 20L and thereby drives the. compressed refrigerant vapor outinto the condenser 2l (not shown in this figure). This continues untilthe liquid seal is broken in 32L and the vapors pass over into thecondenser 3IL, and in the meantime the condensation of vapors in theboiler-condenser 80 has served to draw the liquid from the compressionchamber 20R into the expansion chamber 30R and nally into the measuringchamber 3BR.

This cycle is repeated with alternate compression, first in 20B. andthen in 20L and with the condensing vapors from 30R supplying the heatfor the compression step in 30L.

With the operation of this apparatus as just described, it isadvantageous to use a piston liquid oating on the boiling liquid inchambers 2BR and 20L to seal the boiling liquid and prevent evaporationof the latter into the refrigerant space. Furthermore, .it .isordinarily desirable to use the same piston liquid in both of thechambers ZUR and 20L, so that such slight evaporation as may occur fromthe surface of this liquid may be returned in the cycle. Thus, vaporsfrom the surface of the liquid in 20L will be condensed in therefrigerant side of the apparatus and eventually returned to 20R.` If anexcess of the liquid should thus be distilled over into 20R, it wouldmerely pass over through 82 as a liquid and be restored to 20L. That,however, will not often occur, since as a practical matter, theevaporation comes largely from the surface of the liquid in ZUR and thevapor thus mixed with the refrigerant serves to prevent evaporation in20L.

If it is desired to avoid the use of a piston liquid, or for any otherreason to use the same boiling liquid on both sides of the apparatus,the operation must be the reverse of that just described. That is, the.initial compression will take place in 20L and the second stage in 2DR.Since the higher pressure is in the right-hand part of the eapparatus,the same refrigerant may be used and its boiling point at the higherpressure prevailing on the right-hand side will be enough higher thanits boiling point in the lefthand side to permit the operatic-n of theboilercondenser 80, as already described.

For automatic operation of any of the apparatuses embodying myinvention, the heating supply will ordinarily be controlled by athermostat in the cooled space. If the apparatus is properly designed,its operation may be intermittent and the heating source may be turnedon and'oif as the temperature varies above and below a prescribedtemperature level. I nd it more satisfactory, however, to design theapparatus for continuous operation and to regulate the heat sourceinstead of cutting it olf completely. The apparatusfurthermore, lendsitself perfectly to the various other controls which may be desired,such for example, as cold control, defrosting control, etc.

Although the design of the various parts may be altered and varied tomeet the exigencies of any particular situation or the fancy of adesigner, nevertheless, in many respects the designs shown havebeen'chosen advisedly. Thus, I have found the use of a converging top inthe compression chamber 20 permits greater efliciency because it allowsalmost complete expulsion'bf the refrigerant vapor without driving outthe liquid. The

side of the U-connection 32 which opens into the condenser 3l should bemade small enough -so that it may be substantially cleared of liquid bythe bubbling of vapors therethrough and the air I sure used in theapparatus.

cooling, but no great amount of condensation. The condenser 2l ispreferably made as shown with a riser direct to its top and a gravityflow from` there back to the compressor chamber, through the condensercoils, the float or expansion valveor orifice, and the cooling unit.

I have suggested above certain materials which may be used as boilingliquids; it is to be understood that these are cited merely as examplesof numerous liquids which may be used. 'Ihe choice of a liquid in anyparticular case is determined by certain recognized properties and whenit is understood what properties are necessary, this choice will involvelittle diiiculty.

Primarily, of course, the boiling liquid must be one which boils at areasonable temperature under the highest pressure used in the apparatus,and which condenses above, but preferably not far above, the highestatmospheric temperatures which are likely to occur when at the lowestpres- Of course, if cooling Water is used, the liquid may be allowed tocondense at a lower temperature. Secondly, the

liquid should, for'the sake of economy be one which in the temperaturerange Aused should have low latent and specific heats. Thirdly theliquid must be inert as to the parts ofthe apparatus with which it comesin contact and as to the refrigerant, and preferably -the liquid shouldnot dissolve the refrigerant; although if a thoroughly f efficientpiston liquid is used to seal the boiling liquid from the refrigerant, aliquid may sometimes be chosen which is not entirely inert in thisrespect, or which does dissolve the refrigerant to some extent.Preferably the liquid should be non-inflammable, non-poisonous,possessed of an odor strong enough to give warning if a leak should everoccur andavailable on the market at relatively low price.

When sulphur dioxide is used as refrigerant, I prefer to use pentane oriso-pentane as the boiling liquid. No liquid has as yet been found whichcombines all of the desirable properties enumerated. A

When a piston liquid is used, it will be chosen primarily for its lowvapor pressure. Secondly, it must be .inert with respect to theapparatus materials, the piston liquid and the refrigerant, andpreferably should not dissolve any of them.

. Its specific gravity must be substantially different from that, of theboiling liquid; and unless the apparatus is redesigned to use a heavierpiston liquid, this liquid should be enough` lighter than the boilingliquid always to iloat thereon. If a heavier liquid is preferred in anycase, a well should be provided below the connection from the condenser3l to the expansion chamber 30 and the bottom 'of this well may beconnected to the compression chambeir 20 so that only the piston liquidcan pass into the latter.

When methyl chloride is used as the refrigerant and carbon tetrachlorideor pentane as the boiling liquid, I have found glyoerine as the mostsatisfactory piston liquid.

Numerous variations of the above are possible y utilizing the principleof my invention. Thus it may be used in an absorption cycle; e. g. thecompressor acting as the strong liquor circulating pump and the heatfrom the compressor condenser or from the boiler stack gases or bothbeing used in the generation of the convention absorption cycle.

. When used in the' absorption cycle the strong liquor itself may serveas the boiling liquid, am-

2,oso,c4a

lcooling of this tube is preferably designed to effect monia beingboiled out from the liquor in the expansion chamber and vented, e. g.,through a l, counter current heat-exchanger in the generatoi`l and/orstrong liquor intake line, back to the compression chamber. In this caseI prefer te use a boiler arrangement such as that showr in Fig. 5, i.e., with the heating means within the l expansion chamber. The ammoniagas released in the expansion chamber maybe released at the end of thestroke either through a liquid-seal inverted syphon as in Figs. 1 to 4and 8 to 12 or by means of a valve mechanically or electricallyoperated.

It is an advantage of the presentinvention that it is capable ofinfinite variations to meet the exigencies of varying situations.Numerous other forms of the apparatus may be used and numerous othercontrols; thus, by way of example, when mercury is used as a pistonliquid it may make and break a circuit through contacts positioned inone of the chambers and may thereby control the heating or cooling, theoperation of valves, or any other part of the apparatus. I haveillustrated this by a wiring diagram in Fig. 13. i

In this figure electric current from any source flows in through themain leads and 9|. Upper contacts 92 are in seri'es in this circuit andpositioned within one of the chambers just below the upper mercurylevel. The circuit of a relay 93 is, when open, controlled by thesecontacts 92 but is adapted when once operated'to shunt out the contacts92 through the contacts 94 and thus to remain closed even after thecircuit through the contacts 92 is broken by lowering of the mercurylevel. This relay 93 may also control the heating circuit, etc., throughthe contacts 95.

A second pair of contacts 96 are also in the circuit of the relay 93 andmay be positioned just above the lowest level of the mercury so thatwhen the mercury falls below, this level the relay circuit is broken andits armature will be dropped. Thus the heating will continue from thehigh mercury level to the low and will be shut oi thereafter until thehigh is reached again.

A similar system may be used where the piston or boiling liquid is adielectric by positioning spaced plates of a condenser instead ofcontacts within one of the chambers. the capacity of the condenser withchange of dielectric` may be utilized to operate a relay or othercontrol device.

Valves, -heating or cooling means, etc. may also be controlled'directlyby the liquid level, e. g. by means of floats, or by float operatedswitches. Thus in one case I have used two floats connected by a thinshaft. A lower float at about the low level of the liquid is designed tobalance by its buoyancy the weight of the upper float in the vapor, theupper oat is of sufficient buoyancy when it is submerged to operate amercury switch; and the weight of both floats andthe connecting shaft issuilcient to operate said switch the other way when the liquid leveldrops below the lower oat.

The variation in Referring again toFig. 10, the condenser conl MN... r

ber andthe connection may be from the top of the expansion chamber, asin Fig. or from the top of the condenser chamber, as in Fig. 10, and mayconnect with any other part of the apparatus, e. g. lower in the chamber20 or in the connection 26 or lower in the same chamber, although inthis latter case there will not be venting of fixed gases, as in Fig.10, but only condensation of vapors.

Although it is best to operate this type of pump by vaporization andcondensation in the strict sense without decomposition of any kind,nevertheless it is possible to utilize any reversible change from liquidto gaseous state whether it is a purely physical change or involveschemical reaction or decomposition.

The terms vaporization and condensation as used in the accompanyingIclaims are therefore to be broadly construed to include chemicalreactions, as, for example, is the case with release of ammonia fromammonium hydroxide solution.

I have chosen the phrase oating piston to describe a piston which isdriven by fiuid pressure variations as distinguished from pistons drivenby mechanical means.

Although in the above I have suggested a preferred form of my inventionand various modifications thereof, it is to be understood that these aremerely exemplary of the invention and that it may be embodied innumerous other ways.

What is claimed is:-

1. A refrigerator comprising a compressor which includes a U-shapedhousing forming a compression chamber, an expansion chamber, a measuringchamber, a vaporizer, and superheater, a vaporizable liquid piston, asyphon adapted to feed liquid from the measuring chamber to thevaporizer, a surface combustion heater for said vaporizer andsuperheater, a condenser at a level not lower than the expansion chamberconnected to a part of said housing which is normally below the liquidlevel therein, a U-tube connecting the top of the expansion chamber tothe top of the condenser with the bottom of the U at a levelapproximately that of the liquid therein at the end of the compressionstroke, a

`vent from the top of the condenser to the compression chamber, athermostat near the top of the condenser for controlling the supply offuel to said heater, and a sealing liquid separating the vaporizableliquid from the refrigerant in the compression chamber; a refrigerantcompressor and an evaporator designed and related so as to provide acontinuously descending path for liquid from the highest point of thecondenser through the evaporator and back to the compressor; a stackinto which the products of combustion from the heater pass, an airjacket around the condenser of said compressor and opening into thelower part of said stack, and an air jacket around said refrigerantcondenser andl opening into a lower,part of said stack whereby wasteheat from said compressor will create a draft to draw cooling air oversaid refrigerant condenser.

2. A pump comprising two confined columns of liquid connected belowtheir lowest normal levels, the liquid at the topof one column beingcapable of repeated vaporization and condensa.- tion at the temperaturesand pressures normally occurring therein, and the liquid at the top ofthe other column being one which has a low vapor pressure at thetemperatures normally there occurring and in which the substance to becompressed thereby is relatively insoluble, means confining said columnsand the connecting body of liquid, the volume of said confining meansbeing greater than the volume of the liquid, means for vaporizing liquidover the first column, means for condensing resulting vapors in aseparate space communicable with the vapor space over said first columnand with a part of said confining means into which condensate may bedrained to return to said first column, means adapted to control thecommunication between said condensing means and said vapor space topermit escape of vapors therethrough only after the end of a compressionstroke, and said confining means having valves over the second namedcolumn, one adapted to permit the entry of fluid therethrough when thepressure in said space is reduced and the other adapted to permitexpulsion of iiuid therefrom when the pressure is raised.

3. A pump comprising two confined columns of liquid connected belowtheir lowest normal levels, the liquid at the top of one column beingadapted readily and repeatedly to release a gas which can again become apart of the liquid, and the liquid at the top of the other column beingone which is adapted to drive the material to be pumped, means forconfining said columns and the connecting body of liquid, means forreleasing a gas'from said liquid within the confined space of saidfirst-named column, means for restoring said gas to said liquid in aseparate space communicable with the first, means adapted to control thecommunication therebetween so as to permit escape of gas from the firstcolumn to said space only after the end of a compression stroke, andsaid confining means having valves over the second named column, oneadapted to permit the entry of fluid therethrough when the pressure insaid space is reduced and the other adapted to permit discharge of fluidfrom said space when the pressure is raised.

4. A liquid piston pump comprising a housing including a compressionchamber, an expansion chamber and a connection therebetween below theirlowest normal liquid level, a vaporizable liquid therein, means forvaporizing said liquid communicable with the expansion chamber and aU-passage connecting the upper part of the expansion chamber to anotherpart of said housing, the lower passage of said U being at substantiallythe same level as that of the liquid within the expansion chamber at theend of a compression stroke, whereby said U-passage will form a liquidseal for said vapor space until the end of said stroke whereupon theseal will be broken and the vapor allowed to escape.

5. A pump comprising a U tube, a vaporizable liquid therein, a measuringchamber arranged to be filled by overflow from the top of one side ofsaid U, a boiler connected to said U tube and adapted to be fed by saidmeasuring chamber after the level of liquid in that side of the U isbelow the measuring chamber, and an inverted syphon from the top of thesame side of the U as said boiler and measuring chamber adapted normallyto be closed by a liquid seal, but to syphon vapors from said top of oneside of the U tube to another part thereof when the liquid level on thatside has been forced below a given point in said tube. i

6. A pump as dened in claim 5 which further includes a connection toother side of U whereby 7. A pump as defined in claim which furtherincludes an inverted syphon connected to condenser whereby to condensethe vapors before they are returned to the U-tube.

8. A pump comprising a liquid piston, means for vaporizing a liquid oversaid piston whereby to drive it into a compression chamber, means forcooling said vapor to condense it and thereby to draw the piston backfrom the compression chamber, and means for venting gases from the vaporspace into said compression chamber.

9. A liquid -piston pump comprising a housing including a compressionchamber, an expansion chamber and a connection therebetween below thelowestl normal liquid level therein, a Vaporizable liquid therein, meansfor driving and retracting said liquid piston by vaporization andcondensation, and a body of sealing liquid in said compression chamberseparating the veporizable liquid from the material being pumped, saidsealing liquid being substantially immiscible with the vaporizableliquid, and the material being pumped and having a relatively low' vaporpressure at the operating conditions.

1 10. A pump comprising a series of expansion chambers and acorresponding series of compression chambers, a connection between eachexpansion chamber and' a compression chamber beylow the normal liquidlevels therein, heating means associated with the first one of saidexpansion chambers for vaporizing a liquid to drive down the liquidlevel therein, a heat exchange means connected to each expansion'chamberof the series except the first adapted to effect vaporization of aliquid to Ydrive down the liquid level if said expansion chamber andeach of said heat-exchange means being connected to the expansionchamber next preceding in the series by a connection which is adapted tobe open only at the end of a compression stroke whereby the vaporsexhausted from one expansion chamber are condensed and the liquid of thenext expansion chamber is vaporized by heat-transfer from the vapor tothe liquid in said heat-exchanger, and a condenser assoclatedwith thelast of said series of expansion chambers to condense the vapor utilizedtherein.

11. A multiple stage pump 'as defined in claim 10 in which the outlet ofeach compression chamber of the series except one is connected to theinlet of another compression chamber of the series, whereby the pressureof a fluid may be stepped up successively in the several compressionchambers of the series. i

12. A pump comprising a housing including a vaporizer, an expansionchamber, and a compression chamber, a floating piston therein,

means for heating the vaporizer, means for turning .on said heatingmeans when the piston reaches a position near one end of its travel andfor turning it on when the piston reaches a position .near the other endof its travel.

13. A pump as dened in claim 12 which further comprises a condensercommunicable with the expansion chamber, means for controlling thecommunication therebetween to permit escape of vapors to the condenseronly at the end of a compression stroke, a thermostat in said condenseradapted to cut off the heating means when hot vapors enter the condenserand to tw'n o1- said heating means when s aid vapors are all cooled to atemperature at which they are cindensed.

14. A refrigerator apparatus which compris .s a compressor as defined inclaim 3,A a condenser and an evaporation chamber, the condenser andevaporation chamber being substantially above the level of saidcompressorand the path of refrigerant fluid through said condenser andevaporation chamber to the compressor being substantially consistentlydownward whereby compressor liquid carried over into said refrigeratingpart of the apparatus will flow back into the compressor. g

15. A refrigerating apparatus comprising a compressor having a liquidpiston, a refrigerant condenser and an evaporator all in closed cycle,said condenser and evaporator being above. the level of said liquidpiston and being so related and designed as to provide with intermediateconnections a continuously descending path from the highest pointthereof back to the liquid piston in said compressor adapted to returnto said liquid piston any of its material which may be carried over intothe condenser. i

16. The method of artificial refrigeration which comprises confining arefrigerant vapor over a' liquid piston, alternately expelling saidVapor from the confined space under 'higher pressurev and drawing vaporback at lower pressure, condensing the refrigerant at a level above thepiston, refluxing condensed refrigerant and any entrained piston liquidback to the confined space by a continuously descending path including arefrigerating evaporator.

`17 The m'ethod of pumping fluids which compises confining the fluidover a oating piston, reciprocating said piston byalternate'vaporizationand condensation of a uid on the opposite sidethereof and venting from the vaporization side to the compression sideof said piston fugitive gases which have escapedtc the vaporization sideby solution in the vaporizing liquid.

18. 'I'he combination of a refrigerating device operated by heatexchange at a portion of said device at relatively high temperature withhot gases, and heat exchange at another portion thereof at relativelylow temperature to the atmosphere, a stack, means connected to saidstack surrounding said high temperature heat exchange portions to directthe hot gases passing therefrom into the stack, and means independentlyconnected to the stack surrounding said low temperature heat exchangeportion, adapted to utilize the draft created in the stack by said hotgases to draw air at existing atmospheric. temperature over said coolheat exchange portion, and adapted substantially to prevent said lowtemperature portion fromexposure to heat from the high temperatureportion.

TRUMAN S. SAFFORD.

